Financially Costco Wholesale (NASDAQ: COST) is doing great with revenues that increased by $2.09 billion during the last quarter. Yet the club-store giant might be sitting on very shaky ground because of changing times and economics.

There are some serious threats to Costco lurking out there that many investors do not see or appreciate. Understanding these threats can show you how to avoid taking a major loss if Costco’s sales, revenues, income or stock value suddenly collapse. Knowing such threats can also show you how to cash in on a changing retail environment.

Some Serious Threats to Costco Wholesale Include:

Changing lifestyles. The available data indicates major changes in American lifestyles that bode ill for Costco. Statistics show that younger Americans are less likely to have a driver’s license, cook; data shows that Americans now spend more at restaurants than grocery stores, and are less likely to own a home (only 62.9% of Americans owned a home in 2016 the lowest level since 1965, Bloomberg reported). Costco’s business model is built upon the assumption that Americans will own and use a car; make most of their food purchases at a grocery store, and require home-maintenance supplies. Add Americans’ willingness to abandon suburbs for inner cities and rural areas to the mix and you can see that Costco might not be positioned to capture the next generation of American shoppers.

The aging of America. Everybody can see that Americans are getting older, the average age in the country was 37.4 years in 2015 up from 36.5 a decade earlier, US News and World Reportreported. This is problematic for Costco because older people have less money to spend (the average Social Security payment is around $1,250 a month); and less reason, to spend retired couples are less likely to have kids at homes. Older people are also less likely to be in the physical condition to lug all that stuff home.

Kroger (NYSE: KR) Chief Financial Officer Mike Schlotman told CNBC that US food and related prices went through 20 basis points of deflation in the last quarter. Deflation hurts Costco in two ways, first it takes away its’ competitive advantage by enabling competitors like Kroger, Amazon and Aldi to match or undercut its prices. Second, Costco makes less money off what it sells which will cut into profit at some point. The worst effect of deflation would be to force Costco to raise its membership fees to cover expenses. That might drive customers away and cut into long term profits. A major menace would be Costco’s fuel business becoming unprofitable and unsustainable because of falling prices. Note: I think deflation is the biggest immediate threat to Costco.

Amazon (NASDAQ: AMZN) – Amazon Prime is already a major menace to Costco and the threat will grow if the Whole Foods (NASDAQ: AMZN). If Amazon can succeed in creating a membership club that provides same delivery of groceries, hot meals, dry goods and almost any else it might kill Costco. This would be more convenient, more keeping with American lifestyle changes and more attuned to the habits of Millennials and Generation X. The threat would be magnified 100 times if Amazon Prime would be combined with GrubHub or UberEATS to produce a service that would supply all your hot food, household supplies and groceries at the push of a button. Another threat is that Amazon might soon have 400 brick and mortar locations for pickup of orders and drop off of returns throughout the United States.

Walmart (NYSE: WMT) – Walmart is developing an impressive ecommerce operation and experimenting with same-day delivery and store pickup of orders while expanding its inventory. This includes higher quality items through Bonobos, not to mention very low prices. Walmart.com is now one of the cheapest places to buy office supplies which should worry Costco. A major problem here is that it is now possible to shop at Walmart, without going to Walmart making Walmart more convenient than Costco. Walmart’s vast footprint of stores gives it a readymade network of local and regional fulfillment centers for same-day delivery. One big advantage Walmart has over Amazon is that it operates pharmacies which will be a critical service with an aging population.

Kroger (NYSE: KR) – The nation’s largest standalone grocer has quietly been developing some capabilities that threaten Costco. These include Marketplaces, massive stores that sell hardware and dry goods as well as groceries, same-day delivery including an experiment with Uber, more upscale markets, larger liquor departments, a massive investment in organics and natural food, and a large selection of precooked hot foods in its stores. Some Kroger stores; such as Harris Teeter, now contain pizzerias, others feature Asian cafes and taco counters. A major threat to Costco is Kroger developing a hot food delivery service that can also drop off groceries, prescriptions and dry goods. Kroger is also offering more upscale items, such as gourmet cheese, cutting prices and expanding its footprint to new regions.

Aldi, Trader Joe’s and Lidil – These German-owned grocers are direct threats to Costco; because they offer high-quality products at low prices without the need to buy a membership. Aldi offers convenient smaller stores that are better suited to a more urbanized America. Trader Joe’s competes directly with Costco in wine, gourmet food and natural items. Joe’s also seems to be winning the war for the hearts and minds of Millennial shoppers. Both Aldi and Trader Joe’s are expanding rapidly, while Lidil (basically an Aldi clone) is scheduled to make its’ debut in Virginia this summer.

Costco’s days of relentless revenue and income growth might soon end. The club store might soon be faced with a battle for survival it might not be able to win.